Investigations of18F—p—fluorophenylalanine for pancreas scanning

Abstract

Studies of the distribution of p-fluorophenylalanine-(¹⁴C) and p-fluorophenylalanine-(¹⁸F) (¹⁸F-pFPA) in rat tissues showed pancreas/liver concentration ratios of up to 7·4:1 at one hour after intravenous injection. Clinical trials in four volunteer patients who received 100 to 300 μCi showed that in only one case was a clear image of the pancreas obtained. Analysis of plasma samples showed that ¹⁸F-pFPA was less readily incorporated into plasma proteins than ⁷⁵Se-selenomethionine. Up to 35 per cent of the injected ¹⁸F was recovered in the urine in 12 hours and chromatographic and other analyses suggest that about half the excreted activity was in the form of fluoride. Radiation doses to various organs have been calculated and the doses received by kidney, testes, and whole body were 71, 62, and 46 m rad/mCi respectively.